In the screening of fluidizible suspensions, such as medium consistency paper pulp, it is desirable to utilize a simple yet effective apparatus, and one which will allow the production of a number of different accept streams. Medium consistency pulp typically is pulp having a consistency of about 6-15 percent, and most typically within the range of about 8-12 percent solids. In order to effectively screen such suspensions, it is necessary to fluidize them by producing pulsations and shear forces in the suspension. When the suspension is fluidized the fibers or other solid materials therein move relatively to each other, and can be separated according to different sizes, shapes, or weights utilizing the appropriate screening apparatus.
According to the present invention a simple yet effective screening device is provided which is particularly adapted for screening medium consistency pulp, although it may also be utilized in the screening of other fluidizible suspension. Typical pulps with which the invention can be utilized are chemical pulps, or mechanical pulps such as TMP, CTMP, or the like. Utilizing the invention, it may be possible to effect primary and secondary screening within the same device, thereby saving energy and equipment (and resulting capital investment). Two, three, or more accept streams may be generated from a single screening apparatus.
It is the primary object of the present invention to provide a simple and effective screening apparatus for producing a plurality of different accept streams, and one that is utilizable with a wide variety of suspensions including medium consistency pulp. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.